1. Field of the Invention
The present invention relates to a resist film capable of forming a high precision pattern using an electron beam (EB) or extreme ultraviolet rays (EUV) and the like, which is very suitably used in ultramicrolithography or other fabrication processes such as the production of super LSI or high capacity microchips, resist coated mask blanks and a method of forming a resist pattern using the resist film, and a chemical amplification type resist composition. In particular, the present invention relates to a resist film used in a process using a substrate having a particular underlying layer, resist coated mask blanks and a method of forming a resist pattern using the resist film, and a chemical amplification type resist composition.
2. Description of the Related Art
Microfabrication using a resist composition requires, due to increasing integration of integrated circuits, the formation of ultrafine patterns. Hence, the exposure wavelength also tends to become shorter, for example, from g-rays to i-rays or further to excimer laser light, and for example, the development of the lithography technology using an electron beam is currently proceeding. In addition, due to the miniaturization of patterns to be formed, the thinning of resist films is also proceeding to prevent such a problem that the patterns collapse. In addition, as a resin which is used in a resist composition which forms a resist film of conventional thickness (0.5 μm to 1.0 μm), JP2000-171977A, JP1996-15863A (JP-H8-15863A), JP1993-307262A (JP-H5-307262A), and JP2002-156762A disclose resins having a structure wherein a hydrogen atom of a phenolic hydroxyl group is, for example, substituted with an arylmethyl group.
In order to form ultrafine patterns, the thinning of the resist is required, but which results in lowering of dry etching resistance. In addition, in electron beam lithography, in recent years, the acceleration voltage of an election beam (EB) is allowed to increase to reduce the effects of electron scattering in the resist film (forward scattering). In this case, the electron energy capture rate of the resist film decreases, and the sensitivity thereof decreases. In addition, the effect of the scattering of electrons reflected in the resist substance (back scattering) increases. In particular, in a case of forming isolated patterns with large exposure area, the effect of the back scattering increases, and the resolution of the isolated patterns decreases.
In particular, in a case of patterning onto photomask blanks which are used in semiconductor exposure, since there is a light-shielding film containing heavy atoms in the resist lower layer, the effect of the back scattering caused by the light-shielding film is more remarkable. Accordingly, in the case of forming the isolated patterns on the photomask blanks, in particular, there is a high possibility for the resolution to decrease.
As one way to solve these problems, the use of a resin having a polycyclic aromatic skeleton such as naphthalene has been studied (for example, JP2008-95009A, and JP2009-86354A), but the problems with regard to resolution of the isolated patterns have not been solved. JP2005-99558A uses, as one method for increasing the resolution of the isolated patterns, a resin which contains groups capable of adjusting solubility; however, the resolution has not reached a satisfactory level.
In addition, not only is the microfabrication by the resist composition used directly in the production of integrated circuits, but, in recent years, it has been applied to the preparation of a so-called imprint mold structure, and the like (for example, JP2008-162101A, and The Basis and the Technological Development and the Deployment of Application of Nanoimprint—the Fundamental Technology and the Latest Deployment of Technology of Nanoimprint—Editor: Yoshihiko HIRAI, Publisher: Frontier (published on June, 2006)). Therefore, the important problems to be solved by the invention should satisfy at the same time all of high sensitivity, high resolution (for example, high resolving power, excellent pattern profile, small line edge roughness (LER)), and good dry etching resistance, and a solution is needed to these problems.